Abstract

EFFECT OF VITAMIN A ON THE REGENERATION OF HIND LIMBS IN THE TADPOLES OF RANA BREVICEPS

Sushmita Singh, Swastitapa Kar, Sneha Rani and Animesh Kumar Mohapatra*

ABSTRACT

The last three decades have witnessed an explosion of research on the effect of retinoid (vitamin A derivatives) on the pattern formation in the regenerating amphibian limbs and various other developing systems in vertebrates. The effects of exogenous vitamin A palmitate on limb development and regeneration in anuran tadpoles is very significant as it causes regeneration of complete or nearly complete limbs instead of only the missing distal part altering the proximo-distal pattern of regeneration. Several researchers have reported that vitamin A has an inhibitory effect on tail regeneration from the site of tail amputation but induces the development of ectopic limbs from tail blastema following treatment in the limb bud stage of anuran tadpoles. Such remarkable homeotic transformations have been demonstrated in several anuran species upon treatment with vitamin A. In the present study, investigators have made an attempt to assess the effect of vitamin A on limb regeneration after limb amputation in anuran tadpoles. The mortality was higher in group II than group I. The process of limb regeneration was faster in tadpoles of exposed group in comparison to tadpoles of control group. In group I tadpoles (exposed for 48 hrs) showed normal limb development while in tadpoles of group II (exposed for 96 hrs), majority developed hind limb with thigh, shank and ankle with digits but about 25% of tadpoles showed abnormality in the number of digits. The present findings clearly indicate that vitamin A has a positive effect on the blastema which formed at the site of amputation in replacing the structures appropriate to its proximo-distal position.

Keywords: Regeneration, blastema, homeotic transformation, anuran, ectopic limbs.